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Strongly interacting fermions underpin some of the most challenging problems in condensed matter physics, such as high-temperature superconductivity. The low-energy states of these systems encode their essential microscopic properties, yet…

Strongly Correlated Electrons · Physics 2026-05-05 Henning Schlömer , Liyuan Chen , Susanne F. Yelin , Hong-Ye Hu

Quantum technology promises revolutionizing applications in information processing, communications, sensing, and modelling. However, efficient on-demand cooling of the functional quantum degrees of freedom remains a major challenge in many…

Mesoscale and Nanoscale Physics · Physics 2018-06-13 Kuan Yen Tan , Matti Partanen , Russell E. Lake , Joonas Govenius , Shumpei Masuda , Mikko Möttönen

A mechanical system can be optimally controlled through continuous measurements of its position followed by feedback. We revisit the complete formalism for predicting the performance of such as system without invoking the standard rotating…

Quantum Physics · Physics 2023-03-01 Frederik Werner Isaksen , Ulrik Lund Andersen

Optimization of cyclic stochastic heat engines, a topic spanning decades of research, commonly assumes fixed control or response parameters at discrete points in the cycle-a limitation that often leads to experimentally impractical…

Statistical Mechanics · Physics 2025-07-02 Monojit Chatterjee , Viktor Holubec , Rahul Marathe

Cooling of hadron beams (including heavy-ions) is a powerful technique by which accelerator facilities around the world achieve the necessary beam brightness for their physics research. In this paper, we will give an overview of the latest…

Accelerator Physics · Physics 2009-09-29 L. R. Prost , P. Derwent

Exploiting inherent symmetries is a common and effective approach to speed up the simulation of quantum systems. However, efficiently accounting for non-Abelian symmetries, such as the $SU(2)$ total-spin symmetry, remains a major challenge.…

Quantum Physics · Physics 2024-12-20 Anthony Gandon , Alberto Baiardi , Max Rossmannek , Werner Dobrautz , Ivano Tavernelli

Quantum computation is based on implementing selected unitary transformations which represent algorithms. A generalized optimal control theory is used to find the driving field that generates a prespecified unitary transformation. The…

Quantum Physics · Physics 2009-11-07 Jose P. Palao , Ronnie Kosloff

In this article we use optimal control to maximize the efficiency of a quantum heat engine executing the Otto cycle in the presence of external noise. We optimize the engine performance for both amplitude and phase noise. In the case of…

Quantum Physics · Physics 2015-06-18 Dionisis Stefanatos

There has been considerable progress in the design and construction of quantum annealing devices. However, a conclusive detection of quantum speedup over traditional silicon-based machines remains elusive, despite multiple careful studies.…

Quantum Physics · Physics 2015-09-03 Helmut G. Katzgraber , Firas Hamze , Zheng Zhu , Andrew J. Ochoa , H. Munoz-Bauza

Optimization plays a significant role in many areas of science and technology. Most of the industrial optimization problems have inordinately complex structures that render finding their global minima a daunting task. Therefore, designing…

Disordered Systems and Neural Networks · Physics 2021-09-09 Amin Barzegar , Anuj Kankani , Salvatore Mandrà , Helmut G. Katzgraber

Single-photon cooling is a recently introduced method to cool atoms and molecules for which standard methods might not be applicable. We numerically examine this method in a two-dimensional wedge trap as well as in a two-dimensional…

Quantum Physics · Physics 2014-03-25 V. P. Singh , A. Ruschhaupt

We present the OptiBounce algorithm, a new and fast method for finding the bounce action for cosmological phase transitions. This is done by direct solution of the "reduced" minimisation problem proposed by Coleman, Glaser, and Martin. By…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-05 Michael Bardsley

Optical stochastic cooling (OSC) is a promising technique for the cooling of dense particle beams. Its operation at optical frequencies enables obtaining a much larger bandwidth compared to the wellknown microwave-based stochastic cooling.…

Accelerator Physics · Physics 2018-11-14 Matthew Andorf , Valeri Lebedev , Jonathan Jarvis , Philippe Piot

Optimal control theory is an effective tool to improve parameter estimation of quantum systems. Different methods can be employed for the design of the control protocol. They can be based either on Quantum Fischer Information (QFI)…

Quantum Physics · Physics 2023-06-21 Quentin Ansel , Etienne Dionis , Dominique Sugny

We study the problem of dynamic cooling whereby a target qubit is cooled at the expense of heating up $N-1$ further identical qubits, by means of a global unitary operation. A standard back-of-the-envelope high temperature estimate…

Quantum Physics · Physics 2024-09-26 Lindsay Bassman Oftelie , Antonella De Pasquale , Michele Campisi

Optically trapped nanoparticles have recently emerged as exciting candidates for tests of quantum mechanics at the macroscale and as versatile platforms for ultrasensitive metrology. Recent experiments have demonstrated parametric feedback…

Quantum Physics · Physics 2016-03-23 B. Rodenburg , L. P. Neukirch , A. N. Vamivakas , M. Bhattacharya

We propose an approach for cooling both an artificial atom (e.g., a flux qubit) and its neighboring quantum system, the latter modeled by either a quantum two-level system or a quantum resonator. The flux qubit is cooled by manipulating its…

Superconductivity · Physics 2009-11-13 J. Q. You , Yu-xi Liu , Franco Nori

The most promising quantum algorithms require quantum processors hosting millions of quantum bits when targeting practical applications. A major challenge towards large-scale quantum computation is the interconnect complexity. In current…

Most ions lack the fast, cycling transitions that are necessary for direct laser cooling. In most cases, they can still be cooled sympathetically through their Coulomb interaction with a second, coolable ion species confined in the same…

Laser cooling is a fundamental technique used in primary atomic frequency standards, quantum computers, quantum condensed matter physics and tests of fundamental physics, among other areas. It has been known since the early 1990s that laser…